1. Field of the Invention
The present invention relates to an earthquake-proof leg support structure of an electronic apparatus, such as a computer, placed on a floor and, in particular, relates to a leg support structure in which a plurality of legs downwardly extending from an outer case of an electronic apparatus are slidably supported by leg supporting seats.
2. Description of the Related Art
Electronic apparatuses usually have an outer case in which electronic elements and printed wiring boards are installed. The outer case is supported on a floor by downwardly extending legs. Recently, it has been requested that the legs of electronic apparatuses be made earthquake-proof in structure so the electronic apparatuses are less affected by vibration during an earthquake. However, problems exist in the conventional earthquake-proof leg support structures such as the space for placing the electronic apparatus, the cost of the earthquake-proof leg support structure, and the difficulty of assembly. Under these circumstances, it has been requested to provide a compact and easily assembled leg support structure of an electronic apparatus by which an earthquake-proof action is reliably established.
Japanese Unexamined Patent Publication (Kokai) No. 3-93292 discloses an earthquake-proof leg support structure of an electronic apparatus in which a plurality of legs extend vertically downward from an outer case of the electronic apparatus and dish-shaped leg support seats are arranged under the legs. Each leg support seat has an upper flat smooth surface with which the lower end of the leg slidably engages and a peripheral flange surrounding the upper flat smooth surface. Each leg support seat also includes a damper plate and a friction plate, the friction plate being put on the floor. In the case of an earthquake, the leg support seat follows the floor but the leg of the electronic apparatus is slidable relative to the leg support seat and remains substantially at the original position due to inertia, so the leg displaces relative to the floor to thereby give an earthquake-proof effect.
However, in the conventional earthquake-proof leg support structure, if the amplitude of oscillatory movement of the earthquake is relatively small the leg moves along the upper flat smooth surface of the leg support seat within the range of the upper flat smooth surface, but if the leg is initially not exactly positioned at the center of the upper flat smooth surface of the leg support seat or if the amplitude of oscillatory movement of the earthquake is relatively large so that the leg support seat moves beyond the extent of the radius thereof, the leg may impinge against the peripheral flange of the leg support seat, creating an impact. Also, a frictional force between the leg support seat and the floor prevents the leg from further horizontally moving relative to the leg support seat, generating a moment rotating the electronic apparatus, and there is a possibility of the electronic apparatus falling over.